There have been a few questions about it being a water-table. It is not, but it is fully open underneath and anyone could build a simple water-tray on castors or rollers for it.
We had it set-up for a ventilation/filter system.

Now that I think about it, I believe that we can show you that the actuators/drive motors work by programming it to move maually. It should only take a few minutes to hook it back up and run a couple sweeps for anyone interested.